Abstract: Ｒeferring to the section deformation problem of 3D stretch bending profile，the shape deviation and influential factors of section deformation for multi-point flexible 3D stretch bending profile is investigated on the basis of the independent developed equipment; and the effect of part axial length on part cross section height /width deformation is analyzed． The experiment result shows that，on the upper/lower surface of rectangular tube part，both the concave percentage and concave deformation of part emerged and rose with the increased length from the bending symmetric center point to two sides along with axial direction，the concave deformation value on upper surface is bigger than that of lower surface; both the convex percentage and convex deformation emerged on the inside and outside vertical surface，and the convex percentage and convex deformation value rose with the increased length from the bending symmetric central point to two sides along with axial direction．

Key words: aluminum rectangular tube part, multi-point flexible stretch bending, shape deviation, concave deformation value, convex deformation value